Definition/Introduction
Heinz bodies, initially known as Heinz-Erlich bodies, were first described by Dr. Robert Heinz in 1890. Heinz bodies are indicative of oxidative injury to the erythrocyte. They are inclusions of irreversibly denatured hemoglobin attached to the erythrocyte cell membrane. Studies have shown that anti-oxidants may reduce Heinz body formation.[1]
Oxidative damage may be incurred by external substances or due to hereditary enzyme or hemoglobin defects.[2][3] More significant oxidative damage is believed to increase Heinz body formation and adhesion to the erythrocyte inner cellular membrane. Heinz bodies decrease the elasticity and the deformability of the erythrocyte, increasing the probability of splenic destruction. Splenic macrophages remove the damaged portions of the erythrocyte membrane, resulting in the formation of bite cells. Bite cells and the resulting spherocytes are at increased risk of extravascular hemolysis, which may lead to oxidant-induced hemolytic anemia.
Heinz body production may also produce reactive oxygen species, which can cause intravascular hemolysis leading to hemoglobinemia and hemoglobinuria. In addition, oxidative stress can result in methemoglobinemia; ferrous iron is oxidized to ferric iron, decreasing the oxygen-carrying capacity of hemoglobin.
Heinz bodies may be small or relatively large and prominent. In some instances, a single erythrocyte may have several small Heinz bodies. Heinz bodies stain the same red-pink color of mature erythrocytes with common Wright stains and are basophilic with Diff-Quik stain. Laboratory stains can create confusion with other inclusion anomalies, including the reticulofilamentous material of reticulocytes, Pappenheimer bodies (basophilic iron deposits), Howell-Jolly bodies (nuclear fragments), and Hemoglobin H inclusions (beta-chain tetrameric precipitates).[4] These otherwise difficult-to-visualize inclusions are readily observable in supravital stains like methylene blue.
On microscopy, Heinz bodies are small, dark, round, basophilic masses. They are typically located near the inner membrane of the red blood cell.[5]